Lubricant for pneumatic tools and the like



Patented May 12, 195 3 11 1;iftllNlT-ED" STATE S T NTaww F LUBRICANT FOR PNEUMATIC TOOLS AND J ones .I. Wasson, Union, N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application May is, 1950, l g -SerialNo. 1 3,079

is adapted for-the lubrication; of equipmen Which is,,operated underadverseconditions of; dust, moisture, chemical fumes, and the like, where ordinary, lubricants have been found to be somewhatinadequate. t

In the lubrication of pneumatic tools, suchlasv rock drills and other-equipment operated inmines and under dusty'and wet conditions, some difli- ,culty has been encountered lubrication and .cares- Rock drills are operated frequently under conditions Where the surrounding atmosphere is substantially saturated with moisturevapor and jzfol ims. (o1. 25.2-33.4)

permeatedfwith dust, fumes of-sulfur, and other active materials which quickly corrode andcause wear and other deterioration of the equipment.

Aside from problems of corrosion, equipment ing,.properties. or. oiliness, oplubricity, than conventional mineral oil'lubricant'spossess. I The general problem .of'lubricating rock drills and related equipment has been recognized previously. ,Some efforts have been made toprovide a satisfactory lubricant for the severe uses described above, Thus, in the'U.S. patent to Sproule and King, No. 2,479,424, there is'described a rust inhibiting lubricant'consisting of mineral oil containing as additives small quantities ofthe partial esters of polyhydric alcohols, for example, sorbitan orp-entaerythritol monooleates or monosteal-ates. Various other prior art compositions have employed certain fattyoils, such; as rape,- seedoil, as modifiers for the conventional mineral base lubricant. Products of'ithis typeiwhich are commonly employed as pneumatic drill lubrica'nts have consisted of mineral lubricating oils blended. with about 5 to,15% of a'thickened fatty Quench asfblown frapeseed oil. In cert'aiiifrespects, theseproduc't's have shown quite satisfactory lubricating properties. However, they are frequently unsatisfactory in solution stability, if. ,e., sludging or separation of the modifier fre- .quently occurs, as well as inulOad-Carrying and in ru -preventive. p operties. 4 a

In order to meet the various requirements for lubricants for the pneumatic tools used in severe service, especially underground service, such as rock drills and equipment commonly operating under similar conditions, it appears to be necessary that the several properties of good load-carenvironments, but their combination into a stable,

sludge-free lubricant having all the desired properties for specialized service is another matter.

According to the present invention, these properties may be combined a very satisfactory manner by blending with a suitable mineralbase lubricating oil, preferably'one of viscosity between about 50 and 500 S. S. U. at 100 F., proportions of 0.1 to 4% by weight, based on the total composition, of degras, 0.05 to 5% of a rust inhibiting and water-emulsifying agent, such as an oil-soluble metal sulfonate of alkali or alkaline earth metal, plus about 0.5to about 10% of a compatible extreme pressure agent in the form of a sulfurized fatty oil, such as sperm oil or other and comparable animal fat, such as lard oil, sulfurized to a sulfur content of 2 to 30% by weight, and about 0.05 to about 3% of a synergistic oiliness agent and rust inhibitor, preferably in the form of an ester of an acid of phosphorus, such as tricresyl phosphate or phosphite, or the corresponding trialkyl esters, such as tributyl phosphate orphosphite. It is also desirable to add a small amount, for'example, 0.05 to about 5% maximum of a viscous hydrocarbon polymer. The latter ingredient adds to the tackiness and improves the viscosity index of the lubricant. It increases the resistance of the lubricant tomoisture so that it adheres to the part to be lubricated more effectively when water is present. The preferred polymer is a polybutene-having a molecular weight of not less than 2,000 and not more than 100,000, preferably between 10,000 and 50,000. Other essentially hydrocarbon'polymers and copolymers, such as natural rubber, synthetic rubber like butyl rubber, and polystyrene and alkylated polystyrene may be used, provided they are sufficiently oil-soluble to remain in solution and provided they are compatible with the other ingredients. Sulfurized degras may be combined with unsulfurized degras; and thus replace the sulfurized sperm oil or other animal fat. In a broad sense, a combination of; sulfurizedand unsulfurized animal fat or equivalent, seems to berequired along with the oiliness and thickener or tackiness additives.

' The preferred} rangeof ingredients is from about 86 to about "97% by weight of'lubricating oil withil to 3% deg ra s, 0.1 to 2% of m etal sulfonate, calcium or sodium sulfonate being preferred, particularly the-former, aboutf1to;5%

of sulfurized fatty oil','prefei"ably sperm oil, with sulfur content between 2 and 30%, preferably about 10 to 20%, about 0.5 to 2% of the oiliness agent, tricresyl phosphate being preferred for oiliness although other esters mentioned above are almost as satisfactory, and about the same proportions, namely 0.5 to 2% of a polymer, preferably polybutene or a viscous polymer of similar properties. A broader range preferred is about'172 to 09% of lubricating-oil '(preferably, but not necessarily, of mineral base), 0.1 to of degras, 0.05 to of sulfurized fatty material, (or a combination of 0.15 to 1% of sulfurized and unsulfurized fatty material or" animal origin) plus the sulfonate, ester, and polymer, as given above.

Journal 01 Institute of Petroleum, vol. 32, 1046.

1 ASTM D-157-36.

? S. Army-Navy Specification.

The combination of additives shown in Example Iabove'appears to be necessary to obtain all of the desirable properties. Tests made onblendsv in which one or more oi the additi'ves" were left out resulted in unsatisfactory p uctsfrorn the standpoint of meeting all requ re nents This was particularly true in the case oinieeting the critical load-carrying and humidity cabinet tests. For example, blends s iniilai to Example 1, except not containing sulfurized sperm oil, carried only 2 to 3 weights the Alljnen test and showed humidity cabinet lives of only 72 hours. Other blends containall of the additives except tricresyl phosphate carried only. 2 to 3 weights in the Alrnen test. and gave only 72" hours hui-nidity cabinet livesQ Similar results were obtained on blends without both they sulfurizedsperrn oil and tricres'yl phosphate. Results obtained on these blends are presented in Table H.

Table II 0 Load fiiN-liE-il arrying min 1 y Composmon (Almen Cabinet Test) (Hrs) Example 11 MincralOil+ 1% Tricresyl Phosphate 1%- Polybutena; 2-3 72 2% Degras 0.0% Calcium Sultanate Example III Mineral Oil 3% Sulfurized Sperm Oil 1% Polybutene 2-3 72 2% Degras 011% Calcium Sulfonate EIa'mpZe I V Miner-72 ml i)- t' 1 oy u ene 2% Degras; 2 3 72 016%Calcii1m Sulfonate The above data show the marked inferiority of the experimental materials as compared with the product of Example I (Table I). The mineral oil used in Examples I to IV was the same type and grade in each instance. The presence of polybutene appears to benecessary to give the blends adhesive properties, which prevent the oil from being displaced or thrown off the equipment during service.

While mineral oil is the preferred base lubrican't, it is possible also to use synthetic ester lubricants, such as the dibasic acid esters and the glycol and glycol-ether type lubricants, which have recently come into use. Mineral oil products are generally less expensive and are usually preferred although specific applications may call for the ester type or glycol type oils.

The humidity cabinet test given above is the standard humidity cabinet rusting test wherein a polished steel strip is coated with the lubricant and kept under conditions of approximately relative humidity at a temperature of 13. until first rusting appears. As indicated in the tables above, it is desired to have a humidity cabinet life of at least 100 hours. Plain mineral oil rusts in about one hour. The composition of the present invention (Example I) ran 600 hours before rusting, whereas a conventional prior art rock drill lubricant containing 7% blown rapeseed oil gave a humidity cabinet life of only 24 hours. 'The products of Examples II, III and IV were of intermediate quality.

What is claimed is:

1. A lubricant for pneumatic tools, and the like, consisting essentially of about 86 to 97 parts by weight of mineral base lubricatingoil having a viscosity between 50 and 500 S. S. U. at 100 F., l to 3 parts of degras, 0.1 to 2 parts of oil-soluble calcium petroleum sulfonate, 1 to 5 parts of sulfurized sperm oil containing 10 to 20% of sulfur, 0.5 to 2 parts of trieresyl phosphate and. 0.5. to. 2 parts of polybutene of molecular weight between 10,000 and 50,000.

2, A composition havingapproximately the following formula in percentages by weight:

92.4% mineral lubricating oil 2.0% degras 0.6% oil-soluble calcium sulionate 3.0% sulfurized sperm oil (10 to 20% by weight of sulfur) 1.0% tricresyl phosphate 1.0% polybutene of molecular weight between 15,000 and 30,000.

JONES; I. NASSON.

References Cited in the file of this patent UNITED-STATES PATENTS Number Name Date 2,184,952 Zimmer Dec. 26, 1939 2,270,577 Bergstrom Jan. 20, 1942 2,398,429- Hughes Apr. 16, 1946 2,453,833 Davis Nov. 16, 1948 

1. A LUBRICANT FOR PNEUMATIC TOOLS, AND THE LIKE, CONSISTING ESSENTIALLY OF ABOUT 86 TO 97 PARTS BY WEIGHT OF MINERAL BASE LUBRICATING OIL HAVING A VISCOSITY BETWEEN 50 AND 500 S. S. U. AT 100* F., 1 TO 3 PARTS OF DEGRAS, 0.1 TO 2 PARTS OF OIL-SOLUBLE CALCIUM PETROLEUM SULFONATE, 1 TO 5 PARTS OF SULFURIZED SPERM OIL CONTAINING 10 TO 20% OF SULFUR, 0.5 TO 2 PARTS OFTRICRESYL PHOSPHATE AND 0.5 TO 2 PARTS OF POLYBUTENE OF MOLECULAR WEIGHT BETWEEN 10,000 AND 50,000. 